Process of producing incandescent materials suitable for electric lighting.



basis the common unnoble metals.

NITED STATES'PATENT Errol.

GEORG ALEFELD, OF DARMSTADT, GERMANY, ASSIGNOR TO THE PHARMA- ZEUTISCHESINSTITUT LUDWIG WILI-IELM GANS, OF FRANKFORT-O N- THE-MAIN, GERMANY.

PROCESS OF PRODUCING IIICANDESCENT MATERIALS SUITABLE FOR ELECTRICLIGHTING.

SPECIFICATION forming part of Letters Patent No. 645,198, dated March13, Application filed February 21, 1899. Serial No. 706,362. (Nospecimensi) To all whom it may concern.-

Be it known that I, GEORG ALEFELD, a citizen of Germany, andaresident ofDarmstadt, in the Empire of Germany, have invented a 5 new and usefulImprovement in the Produc tion of Incandescent Materials Suitable forElectric Lighting, of which the following is a specification.

Incandescent materials consisting of an into ner conductor having anouter covering of metallic oxids are known. Their manufacture, however,is attended with great difficulties. Neither galvanic nor mechanicalcoatings give satisfactory results, since all attempts to produce aneven but sufficientlythin coating have been unsuccessful. The

' object of my invention is to overcome these difficulties.

In my process the so-called lusters or lustrous preparations of themetals are used which'have heretofore been sold and used for thedecoration of porcelain, glass, 850. These lusters are organic compoundsof metals (resin, acid compounds, or sulfureted resin 2 5 compounds, orproducts of the decomposition of metallic chlorids produced by heatingthem with lavender-oil) which are. mixed in their application with anethereal oil, such as lavender-oil. Such lusters of many of the metalsare well known, but there is a very remarkable difierence between thosewhich have for their basis the so-called noble metals-that is, gold,silver, and all the metals of the platinum group-and those which havefor their The first named when applied upon porcelain, glass, or metaland then heated to a high temperature leave behind a thin skin of metal,while the lusters of the unnoble met- 0 als when treated in thesamemanner form a skin of metallic oxid.

My completed incandescent consists of a core or interior of one of thehighly-infusible metals of the platinum group-such as 0s- 5 mium,rhodium, ruthenium, 850., or alloys of the same-covered by an adhesivecoherent coating of one of the luminous earthy metals, such as thorium,didymium, cerium, erbium, zirconium, and the like. A mixture ofninetynine per cent. of thorium and one per cent.

of cerium seems best adapted for this pur-' pose as far as I am atpresent informed;

1 will now describe the two phases of my process, first, the productionof the core, and, 5 secondly, the application of the coating to thecore. I, P

1. Production of the c0re.Upon small rods,- tubes, or disks of glass orporcelain is spread a solution of a ceramic luster of a highly-infusible metal of the platinum group, such as ruthenium, rhodium, osmium,and the like. Lustrous preparations of these metals may be prepared inan analogous manner to those of gold, silver, and platinum. The smallrods, tubes, or disks and the like are coated in straight or' curvedlines or in any other form with the preparations and then burned in.Mixtures also of these different metals are suitable and form alloys,which are pro duced in the manner above described. When necessary, theskin of metal thus formed can be strengthened by electrodeposition.

Though known inthe art, it may not be amiss to mention that while thelusters of the non-oxidizable noble metals may be burned in withoutprecaution against oxidation the lusters of the oxidizable metals, suchas osmium, should be burned in in a reductionfiame, or, better still, ina closed muffle in the presence of a reducing or neutral gas, such asilluminating-gas, hydrogen, or carbonic acid.

The next step is to detach the skin of the noble metal. In order to dothat, the glass or the porcelain must be removed, which is done veryeasily by treating it with hydrofluoric acid or even with hydrochloricacid, provided a special kind of glass soluble in this acid has beenused. In so doing it is not at all necessary that the whole of theglass, porcelain, &c., be dissolved before one is able to detach themetal-skin; but generally after a brief treatment with the hydrofluoricacid the metal-skin can bev removed as easily as, for instance, apostage-stamp stuck on paper can be removed from the latter by dippinginto 5 water; but these skins of the 'noble metal, particularly if verythin, are easily torn. To avoid such accidents,it is advisable to brushover the skin ofnoble metal with some form of tough varnish, such ascollodion or a gutta- I00 able.

This hereinbefore described method of making the core or interior of myincandescent materials being not very convenient for several reasons, asecond method has been d.e-

vised by me which is much better adapted to the purpose. This newprocess in question has not only been found adapted for producing thecore of my incandescents, but serves also for the manufacture of metalfoil or leaf, which hitherto could only be obtained by hammering. In anapplication of even date herewithfSerial No. 706,361, I have explicitlydescribed this method of producing metal foil or leaf. Therefore here Iwill only repeat the principal point-s of the process.

A solution of a ceramic luster elf-an unnoble metal-for example, theresin-acid compound mixed with an ethereal oil-isspread upon the surfaceof porcelain, glass, metal, or any other material which isacid-resistant and capable of enduring unimpaired the tem peraturenecessary to burn in the ceramic luster employed. The luster may besubstituted'by fluxes easily soluble in acid, such as borosilicates orphosphates of soda, &c. Then the luster or' its substitute is burned in.Upon this bed, as it may be called, a lustrous preparation of thedesired noble metal is laid and burned in in the usual manner. This maybe repeated until the desired thickness is attained, or it may bethickened by electrolytic deposition of the metal. Thenthe skin of thenoblemetal is detached by immersing the plate in a solvent (usuallyinorganic and strong organic acids) of the bed, which is thus dissolvedaway, leaving the skin of. the noble metal free. Before putting theplate into the solvent the skin may be covered with tough varnish, suchas collodion or a gutta-percha solution, as hereinbefore described. Thefoil or leaf, still covered with the protecting-varnish, it such varnishis used, is formed into a thin rod or thread by rolling it upon itselfor into a tube by rolling it around a thread or string or in any othersuitable manner. The said rod or thread or tube isthen formed into thedesired shape, and the collodion or varnish and the thread or stringcore, if any, is burned or dissolved away. As shown in my saidapplication of even date herewith, Serial No.

706,361, metal foil or leaf may by its method be produced in the form ofa sheet or in the form of any pattern, so the core of my in candescentbodycan in accordance with that inventionbegiven any desired form-forexample, that of a network--by laying the luste'r upon its bed inareticulated pattern, burning it in, and then forming it into a mantlelike those usedv in gas incandescent lighting, or such a reticulatedmantle, or, indeed, almost any form, can be produced by giving thedesired form to the porcelain or its substitute, to which the lustersare applied before the first firing.

2. Applying the coating to the core-This core, produced as described,may be used in this form as an-incandescent body. In order to strengthenits illuminating power, it may be coated with luminous earthy metal.This second step of my invention is carried out as follows: Upon thecore, formed, as hereinbefore described, of one of the highly-infusiblemetals of the platinum group, is applied a coating of a ceramic resinluster of the desired luminous earthy metal, such as a mixture ofninety-nine per cent. thorium and one per cent. cerium, by dusting iton.in the form of'a powder or by painting it onor dipping intoor otherwiseapplying a solution or mixture of said resin ceramic luster with anethereal oil, such as lavender-oil. It is then fired in the usualmanner, and. the result is an incandescent adapted to incandescentelectric lighting, which. consists of acore-of one of thehighly-infusible metals of. the platinum group covered with an adherentglasslike coating of a luminous earthy metal. A great practicaldiiterence is found in the behavior of these resin compounds of. theluminous earthy metals and that of their usual soluble saltsnitrates,acetates, &c.since with the latter, when fired, the oxid is left behindas a raw powder which has little adhesion, while with the resincompounds avery adherent glass-like coating isproduced. My incandescentcan then be introducedinto an electric circuit in the usual manner andmay be used. as asubstitute for the ordinary carbon filament, in a bulb,which in case the core contains one of those-metals of the platinumgroup which are oxidizable in the air, such as osmium, can be evacuatedor filled with a reducing or neutral gas, such as illuminatingrgas,hydrogen, or carbonic acid; The core is heated, by the electric currentand heats, in its turn, the exterior coating of the luminous earthymetal to incandescence.

The temperature to which the electric incandescent bodies are heated bythe current being far higher than that reached by Auersincandescentlight,even those kinds of earthfor example, lime, magnesia,&o.can be em ployed of which thep'ower of light emission is stilltrifling at the temperature of Auer light, but increases considerably ata higher temperature.

Having thus described my invention, What I claim as new,,and desire topatent, is-- 1. The withinfdescribed process of producing bodiessuitable for incandescent electric lighting, which consists: first, inwholly or partially coveringa suitable bed'with a-lustrons preparationof one or more of the highlyinfusible metals of the platinum group andburning the same in; second, detaching the resultant metallic film fromthe bed by the action of solvents which will attack the bed and not thefilm; and third, forming the said metallic film into the desired shape.

2. The within-described process of producing bodies suitable forincandescent electric lighting, which consists: first, in wholly, orpartially covering a suitable bed with a lustrous preparation of one ormore of the highlyinfusible metals of the platinum group and burning thesame in; second, covering the metallic film so produced with a toughprotective varnish; third, detaching the resultant metallic film fromthe bed by the action of solvents which will attack the bed and not thefilm; and fourth, forming the said metallic film into the desired shape.

, 3. The within-described process of producing bodies suitable forincandescent electric lighting which consists: first, in wholly orpartially covering an acid and heat resisting plate or matrix with aceramic lustrous preparation of one or more of the unnoble metals andburning the same in; second, laying upon this coating of unnoblemetallic oxid a lustrous preparation of one or more of thehighly-infusible metals of the platinum group and burning it in; third,detaching the resultant film of the said highly-infusible metal by theaction of a solvent which will attack the unnoble metallic oxid but notthe highly-infusi ble metal film, and lastly forming the detached filmof the highly-infusible metal into the desired shape.

4. The within-described process of producing bodies suitable forincandescent electric lighting which consists: first, in wholly orpartially covering an acid and heat resisting plate or matrix with aceramic lustrous-preparation of one or more of the unnoble metals andburning the same in; second, laying upon this coating of unnoblemetallic oxid a lustrous preparation of one or more of thehighly-infusible metals of the platinum group and burningitin; third,covering the metallic film so produced with a tough protective varnish;fourth, detaching the resultant film of the said highly-infusible metalby the action of a solvent which will attack the unnoble metallic oxidbut not the highly-infusible metal film, and lastly forming the detachedfilm of the highly-infusible metal into the desired shape. v v

5. The within-described process of producing bodies suitable forincandescent electric lighting,which consists: first, in wholly orpartially covering a suitable bed with a lustrous preparation of one ormore of the highly-infusible metals of the platinum group and burningthe same in; second, detaching the resultant metallic film from the bedby the action of solvents which will attack the bed and not the film;third, forming the said metallic film into the desired shape; andfourth, coating said so-formed metallic film with ceramic resin lusterof one or more of the luminous earthy metals and burning the same in.

6. The within-described process of producing bodies suitable forincandescent electric lighting,which consists: first, in wholly orpartially covering an acid and heat resisting plate or matrix with aceramic lustrous preparation of one or more of the unnoble metals andburning the same in; second, laying upon this coating of unnoblemetallic-oxid a lustrous preparation of one or more of thehighly-infusible metals of the platinum group and burning it in; third,detaching the resultant film of the said highly-infusible metal by theaction of a solvent which will attack the unnoble metallic oxid but notthe highly-infusible metal film; fourth',forming the ,detached film ofthe highly-infusible metal into the desired shape; and lastly, coatingsaid so-formed metallic film with ceramic resin luster of one or more ofthe luminous earthy metals and burning the same in.

7. The within-described process of producing bodies suitable forincandescent electric lighting, which consists: first, in wholly orpartially covering a suitable bed with a lustrous preparation of one ormore of the highly-infusible metals of the platinum group and burningthe same in; second, covering the metallic film so produced with a toughprotective varnish; third, detaching the resultant film from the bed bythe action of solvents which will attack the bed and not the film;fourth, forming the said metallic film into the desired shape; fifth,removing the tough protective varnish from the metallic film by means ofa solvent or by burning, using either fire or the electric current, andsixth, coat= ing the metallic film with ceramic resin luster of one ormore of the luminous earthy metals and burning the same in.

8. The within-described process of producing bodies suitable forincandescent electric lighting,which consists; first, in wholly orpartially covering an acid and heat resisting plate or matrix with aceramic lustrous preparation of one or more of the unnoble metals andburning the same in; second, laying upon this coating of unnoblemetallic oxid a lustrous preparation of one or more of thehighly-infusible metals of the platinum group and burning it in; third,covering the metallic film so produced with a tough protective varnish;fourth, detaching the resultant film of the said highly-infusible metalby the action of a solvent which will attack the unnoble metallic oxidbut not the highly-infusible metal film; fifth, forming the saidmetallic film into the desired shape; sixth, removing the toughprotective varnish from the metallic film by means of a solvent or byburning, using either fire or the electric current; and seventh, coatingthe metallic film with ceramic resin luster of one or more of theluminous earthy metals and burning the same in.

4 mam 9. As a next article of manufacture an in- SignedatFrankfort-on-the-Main,in the Emcandescent body adapted to incandescentpire of Germany, this 27th day of January,-1o electric lighting,consisting of a core of one A. D. 1899.

or more of the hi hiy-infusible metals of the 5 platinum group, brovidedwith a glass-like GEORG ALEFELD coherent and adherent exterior coatingof in- Witnesses: minous earthy metal as produced by burning RICHARDGUENTHER,

in a ceramic resin luster 0f the same. JEAN GRUND.

